Endometriosis is a condition afflicting women of child-bearing age which is characterized by the growth of endometrial tissue in areas outside the uterus. These extrauterine endometrial growths are a leading cause of pelvic pain and can also cause infertility. Endometrial growths can occur in a variety of locations, including the lining of the pelvic cavity and the outer surface of the uterus, and can also occur outside the abdomen, for example, in the lung.
As is the case with the uterine lining, extrauterine endometrial growths typically respond to the varying levels of estrogen associated with the menstrual cycle. Thus, endometrial growths proceed through a cycle of proliferation and breakdown. Unlike the uterine lining, however, the body is unable to shed the extrauterine endometrial growths, and breakdown of this tissue results in internal bleeding, inflammation of the surrounding area and formation of scar tissue. A number of complications can also arise, including rupture of growths, which can spread the growths to new regions of the body, and the formation of adhesions.
The most common symptoms of endometriosis include constant pelvic pain, infertility, low sacral backache, and heavy or irregular bleeding. The degree of pain does not correspond to the size or extent of endometrial growths, and significant pain can result even from microscopic growths. Endometrial implants can destroy ovarian and tubal tissue. Several disorders of menstrual cyclicity and ovulation have been suggested as a basis for the infertility caused by mild endometriosis. More subtle problems in folliculogenesis in endometriosis patients have been reported, including lower serum estradiol levels, smaller follicle size during follicular growth, and lower oocyte fertilization rates and pregnancy rates in assisted reproduction. Problems with ovum pickup by the fallopian tube and embryo implantation in the endometrium have also been suggested.
Currently, a definitive diagnosis of endometriosis can be made only upon laparoscopic examination of the abdomen. This is a surgical procedure performed under local anesthesia and can indicate the extent and location of extrauterine endometrial growths. Laparoscopic examination is essential because symptoms of endometriosis are similar to the symptoms of other conditions, including ovarian cancer. Prevention of endometriosis is not currently possible; however, treatment options are available based on the patient's desire for future fertility, symptoms, the stage of disease, and to some extent, age. Possible treatment options include analgesic treatments, such as nonsteroidal anti-inflammatory agents and prostaglandin synthetase-inhibiting drugs, and hormonal therapy, which may be given as a means for interrupting the cycles of stimulation and bleeding of endometriotic tissue. Common hormonal therapies include oral contraceptive pills; progestational agents, which cause decidualization in the endometriotic tissue; danazol, a weak androgen that is the isoxazole derivative of 17α-ethinyl testosterone (ethisterone); and gonadotropin-releasing hormone (GnRH) agonists, which are analogues of the 10-amino-acid polypeptide hormone GnRH and act via the suppression of gonadotropin secretion, resulting in elimination of ovarian steroidogenesis and suppression of endometrial implants. Lastly, surgical treatment, including laparoscopic resection, ablation of minimal or mild endometriosis, presacral neurectomy and uterosacral ligament ablation, may be performed to excise or destroy all endometriotic tissue, remove all adhesions, and restore pelvic anatomy to the best possible condition.
Despite the treatments available for endometriosis, it would be beneficial to provide specific non-invasive methods and reagents for the diagnosis, staging, prognosis, monitoring, and treatment of endometriosis and endometriosis-related diseases, or to indicate a predisposition to such for preventative measures.